Control device

ABSTRACT

The present invention relates to a control device that controls a vehicle drive device in which a rotary electric machine is provided in a power transfer path that connects between an internal combustion engine and wheels and in which a first friction engagement device is provided between the internal combustion engine and the rotary electric machine and a second friction engagement device is provided between the rotary electric machine and the wheels.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2011-157992 filed onJul. 19, 2011, Japanese Patent Application No. 2011-150169 filed on Jul.6, 2011, Japanese Patent Application No. 2012-013257 filed on Jan. 25,2012 including the specification, drawings and abstract is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a control device that controls avehicle drive device in which a rotary electric machine is provided in apower transfer path that connects between an internal combustion engineand wheels and in which a first friction engagement device is providedbetween the internal combustion engine and the rotary electric machineand a second friction engagement device is provided between the rotaryelectric machine and the wheels.

DESCRIPTION OF THE RELATED ART

A device described in Japanese Patent Application Publication No.2010-149640 (JP 2010-149640 A) is already known as an example of thecontrol device that controls a vehicle drive device described above.Hereinafter, in the description in the “Description of the Related Art”section, reference numerals used in JP 2010-149640 A (and the names ofcorresponding members as necessary) are cited in brackets fordescription. The control device is configured to execute internalcombustion engine start control in which the internal combustion engine[engine E] is started using torque of the rotary electric machine [motorMG] by bringing the first friction engagement device [first clutch CL1]into a direct engagement state from a state in which the internalcombustion engine is stopped and the first friction engagement device isdisengaged. When the internal combustion engine start control isexecuted, rotational speed feedback control in which the rotationalspeed of the rotary electric machine is caused to coincide with a targetrotational speed is executed. In this event, a target transfer torquecapacity [target clutch transfer torque command TCL2] for the secondfriction engagement device [second clutch CL2] in the speed changemechanism [automatic transmission AT] is controlled such that the secondfriction engagement device transfers predetermined torque in a slipengagement state.

The control device according to JP 2010-149640 A is configured to decidethe target transfer torque capacity for the second friction engagementdevice on the basis of a difference [torque deviation amount ΔT] betweenactual torque of the rotary electric machine and maximum torque that canbe output from the rotary electric machine, or a difference inrotational speed [rotational speed difference ΔN] between engagementmembers on both sides of the second friction engagement device. Thisallows to suppress torque fluctuations due to an error in transfertorque capacity of the second friction engagement device by optimizingthe slipping (slip) state of the second friction engagement device.

SUMMARY OF THE INVENTION

In the device according to JP 2010-149640 A, however, the control fordeciding the target transfer torque capacity for the second frictionengagement device described above is only executed in a period in whichthe first friction engagement device is in the slip engagement state,and is not executed after the first friction engagement device isbrought into the direct engagement state. In the device according to JP2010-149640 A, the first friction engagement device is controlled to apredetermined transfer torque capacity to be brought into the slipengagement state. Therefore, in the case where there is an error intransfer torque capacity of the first friction engagement device, atorque difference may be caused in torque transferred to the wheels viathe second friction engagement device when the second frictionengagement device is brought from the slip engagement state into thedirect engagement state and the rotational speed feedback control forthe rotary electric machine is terminated to start torque control forthe rotary electric machine. This may cause occupants of the vehicle tofeel a shock. Such an issue is not only caused in the case where thefirst friction engagement device is brought into the slip engagementstate to start the internal combustion engine, but also in the casewhere the first friction engagement device is brought into the slipengagement state during operation of the internal combustion engine.Even in the case where the first friction engagement device is in thedirect engagement state and is not slipping, in addition, a similarissue may be caused in the case where there is an error in output torqueof the internal combustion engine.

In view of the foregoing, it is desired to provide a control device thatcan suppress a torque difference caused when the second frictionengagement device is brought from the slip engagement state into thedirect engagement state irrespective of an error in torque of theinternal combustion engine or an error in transfer torque capacity ofthe first friction engagement device.

According to an aspect of the present invention, a control devicecontrols a vehicle drive device in which a rotary electric machine isprovided in a power transfer path that connects between an internalcombustion engine and wheels and in which a first friction engagementdevice is provided between the internal combustion engine and the rotaryelectric machine and a second friction engagement device is providedbetween the rotary electric machine and the wheels. The control deviceexecutes rotational state control in which a rotational state of therotary electric machine is controlled such that a target rotationalstate is established with torque of the internal combustion enginetransferred to the wheels while a hydraulic pressure supplied to thefirst friction engagement device is controlled such that a rotationalstate of the internal combustion engine coincides with a targetrotational state with both the first friction engagement device and thesecond friction engagement device in a slip engagement state, or withtorque of the internal combustion engine transferred to the wheels withthe first friction engagement device in a direct engagement state andwith the second friction engagement device in a slip engagement state;and the control device executes hydraulic pressure regulation control inwhich a hydraulic pressure supplied to the second friction engagementdevice in the slip engagement state is controlled on the basis of torqueof the rotary electric machine produced during the rotational statecontrol while the second friction engagement device is transitioned fromthe slip engagement state to a direct engagement state.

The term “rotary electric machine” refers to any of a motor (electricmotor), a generator (electric generator), and a motor generator thatfunctions both as a motor and as a generator as necessary.

The term “slip engagement state” means a state in which two engagementmembers to be engaged with each other by the subject friction engagementdevice are engaged with each other with a rotational speed difference soas to transfer a drive force between each other. The term “directengagement state” means a state in which the two engagement members areengaged with each other so as to rotate together with each other. The“disengaged state” means a state in which no rotation or drive force istransferred between the two engagement members.

The term “rotational state” is used to include a rotational position, arotational speed, and a rotational acceleration. Thus, the term“rotational state control” includes rotational position feedback controlin which the rotational position of the subject to be controlled iscontrolled such that a target rotational position is established,rotational speed feedback control in which the rotational speed of thesubject to be controlled is controlled such that a target rotationalspeed is established, rotational acceleration feedback control in whichthe rotational acceleration of the subject to be controlled iscontrolled such that a target rotational acceleration is established,and so forth.

With the hydraulic pressure supplied to the first friction engagementdevice controlled such that the rotational state of the internalcombustion engine coincides with the target rotational state with thefirst friction engagement device in the slip engagement state, or withthe first friction engagement device in the direct engagement state, asin the configuration described above, torque of the internal combustionengine can be transferred as it is to the rotary electric machine sidevia the first friction engagement device. That is, torque of theinternal combustion engine that is not affected by an error in transfertorque capacity of the first friction engagement device can betransferred to the rotary electric machine side. Here, in the case wherethere is an error in output torque of the internal combustion engine,the rotational state of the rotary electric machine does not temporarilycoincide with the target rotational state because of the error. Byexecuting the rotational state control, however, the output torque ofthe rotary electric machine is sequentially increased and decreased sothat the rotational state of the rotary electric machine coincides withthe target rotational state. When the second friction engagement deviceis transitioned from the slip engagement state to the direct engagementstate in this state, the rotational speed of the rotary electric machineis defined uniquely in accordance with the rotational speed of thewheels, and the rotary electric machine outputs predetermined torque. Inthis event, a torque difference matching the difference between theoutput torque produced during the rotational state control and thepredetermined torque produced after the second friction engagementdevice is transitioned to the direct engagement state may be caused intorque transferred to the wheels around the transition in state of thesecond friction engagement device.

In this respect, according to the configuration described above, theoutput torque of the rotary electric machine produced during therotational state control can be caused to approach the predeterminedtorque produced after the second friction engagement device istransitioned to the direct engagement state by appropriately controllingthe hydraulic pressure to be supplied to the second friction engagementdevice in the hydraulic pressure regulation control on the basis of theoutput torque. Hence, a torque difference caused when the secondfriction engagement device is transitioned from the slip engagementstate to the direct engagement state can be suppressed.

Here, the control device may further execute target torque decisioncontrol in which target torque for the rotary electric machine isdecided on the basis of a difference between a required drive force fordriving the wheels and torque transferred from the internal combustionengine to the rotary electric machine; the control device may execute asthe rotational state control rotational speed feedback control in whicha rotational speed of the rotary electric machine is controlled so as tocoincide with a target rotational speed by adding correction torque tothe target torque; and the control device may execute the hydraulicpressure regulation control on the basis of the required drive force andthe correction torque for the rotational speed feedback control.

In one form of a control scheme for the rotary electric machine, as inthe configuration, the target torque decision control and the rotationalspeed feedback control can be combined with each other. In this case,the rotary electric machine is controlled on the basis of the targettorque decided through execution of the target torque decision controland the correction torque added to the target torque through executionof the rotational speed feedback control. According to theconfiguration, operation of the rotary electric machine can becontrolled with high following performance.

In addition, in one form of a control scheme for the second frictionengagement device, as in the configuration, control for the suppliedhydraulic pressure performed on the basis of the required drive forceand control for the supplied hydraulic pressure performed on the basisof the correction torque for the rotational speed feedback control canbe combined with each other. By executing the hydraulic pressureregulation control on the basis of both the required drive force and thecorrection torque for the rotational speed feedback control, operationof the second friction engagement device can be controlled with highfollowing performance, and occurrence of a torque difference can beeffectively suppressed.

In addition, the control device may execute the hydraulic pressureregulation control on the basis of the correction torque calculated withexclusion of an amount corresponding to rotation-varying torque for therotary electric machine for varying the rotational speed of the rotaryelectric machine toward the target rotational speed in the rotationalspeed feedback control.

The correction torque to be added to the target torque for the rotaryelectric machine in the rotational speed feedback control may includerotation-varying torque (inertia torque) for varying the rotationalspeed of the rotary electric machine toward the target rotational speed,besides torque for compensation for an error in torque of the internalcombustion engine.

In the configuration described above, in view of this respect, thecorrection torque is calculated with the exclusion of an amountcorresponding to the rotation-varying torque. Thus, the hydraulicpressure to be supplied to the second friction engagement device can bedecided appropriately with a steady error due to an error in torque ofthe internal combustion engine reflected in the hydraulic pressureregulation control, which allows to effectively suppress occurrence of atorque difference.

In addition, in the hydraulic pressure regulation control, a targettransfer torque capacity for the second friction engagement device maybe decided on the basis of a value computed by integrating thecorrection torque over time, and the hydraulic pressure supplied to thesecond friction engagement device may be decided on the basis of thetarget transfer torque capacity.

By deciding the target transfer torque capacity for the second frictionengagement device as in the configuration, the correction torque can begradually reduced to become zero in the course of time. Hence, a torquedifference caused around the transition of the second frictionengagement device from the slip engagement state to the directengagement state can be effectively suppressed.

In addition, although the transfer torque capacity of the secondfriction engagement device is varied by performing the hydraulicpressure regulation control, the transfer torque capacity of the secondfriction engagement device can be varied gradually by gradually reducingthe correction torque. Thus, it is possible to suppress an uncomfortablefeeling to be given to a driver of the vehicle because of abruptvariations in drive force transferred to the wheels along withvariations in transfer torque capacity of the second friction engagementdevice.

In the case where the second friction engagement device is brought fromthe slip engagement state into the direct engagement state and controlfor the rotary electric machine is transitioned from the rotationalspeed feedback control to the torque control, the correction torqueproduced in the rotational speed feedback control is momentarilycanceled, and the rotary electric machine outputs the target torquedecided through execution of the target torque decision control. At thistime, a torque difference with a magnitude corresponding to thecorrection torque may be caused in torque transferred to the wheelsaround the transition in engagement state of the second frictionengagement device as discussed above.

In view of this respect, the aspect of the present invention can besuitably applied to a configuration in which: the control device mayfurther execute torque control in which output torque of the rotaryelectric machine is controlled so as to coincide with the target torque;and in the case where it is determined during execution of the hydraulicpressure regulation control that the second friction engagement devicehas been brought into the direct engagement state, control for therotary electric machine may be transitioned from the rotational speedfeedback control to the torque control. With this configuration, atorque difference caused around the transition in engagement state ofthe second friction engagement device can be effectively suppressed.

In addition, in the case where the correction torque has not become zerowhen it is determined that the second friction engagement device hasbeen brought into the direct engagement state, the control deviceexecutes transition torque control in which the output torque of therotary electric machine is gradually varied from torque produced duringthe rotational speed feedback control to the target torque along withthe transition from the rotational speed feedback control to the torquecontrol.

According to the configuration, occurrence of a torque difference can besuppressed by gradually varying torque of the rotary electric machine tothe target torque by gradually reducing the correction torque throughthe transition torque control even in the case where the second frictionengagement device is brought into the direct engagement state when thecorrection torque produced in the rotational speed feedback control isnot zero.

In addition, the hydraulic pressure regulation control may be executedin a predetermined period at and before a time at which the secondfriction engagement device is transitioned from the slip engagementstate to the direct engagement state, the predetermined period includingthe time of the transition.

According to the configuration, a torque difference caused at the timeof the transition of the second friction engagement device from the slipengagement state to the direct engagement state can be effectivelysuppressed through the hydraulic pressure regulation control executed inthe predetermined period at and before the time of the transition.

In addition, the control device may execute the hydraulic pressureregulation control continuously in a period after the second frictionengagement device is brought into the slip engagement state and beforethe second friction engagement device is transitioned to the directengagement state.

According to the configuration, a torque difference caused at the timeof the transition in engagement state of the second friction engagementdevice can be effectively suppressed through the hydraulic pressureregulation control executed all over the period after the secondfriction engagement device is brought into the slip engagement state andbefore the second friction engagement device is transitioned to thedirect engagement state.

In addition, in the hydraulic pressure regulation control, a targettransfer torque capacity for the second friction engagement device maybe decided on the basis of torque of the rotary electric machinenecessary to cause the rotational state of the rotary electric machineduring the rotational state control to coincide with the targetrotational state, and the hydraulic pressure supplied to the secondfriction engagement device may be decided on the basis of the targettransfer torque capacity.

According to the configuration, the hydraulic pressure supplied to thesecond friction engagement device during the hydraulic pressureregulation control can be decided appropriately on the basis of thetarget transfer torque capacity for the second friction engagementdevice which is decided on the basis of torque necessary to cause therotational state of the rotary electric machine during the rotationalstate control to coincide with the target rotational state. By decidingthe target transfer torque capacity for the second friction engagementdevice as in the configuration, in addition, it is possible to graduallyreduce torque necessary to cause the rotational state of the rotaryelectric machine to coincide with the target rotational state. That is,the output torque of the rotary electric machine produced during therotational state control can be caused to approach the predeterminedtorque produced after the second friction engagement device istransitioned to the direct engagement state. Hence, a torque differencecaused around the transition of the second friction engagement devicefrom the slip engagement state to the direct engagement state can beeffectively suppressed. Further, although the transfer torque capacityof the second friction engagement device is varied by performing thehydraulic pressure regulation control, the transfer torque capacity ofthe second friction engagement device can be varied gradually bygradually reducing torque necessary to cause the rotational state of therotary electric machine to coincide with the target rotational state.Thus, it is possible to suppress an uncomfortable feeling to be given toa driver of the vehicle because of abrupt variations in drive forcetransferred to the wheels along with variations in transfer torquecapacity of the second friction engagement device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a schematic configuration of avehicle drive device and a control device for the vehicle drive deviceaccording to an embodiment;

FIG. 2 is a schematic diagram illustrating the basic concept ofhydraulic pressure regulation control;

FIG. 3 is a block diagram showing a detailed configuration of a rotaryelectric machine control section and a hydraulic pressure regulationcontrol section;

FIG. 4 is a time chart showing an example of operation states of variouscomponents during execution of the hydraulic pressure regulationcontrol;

FIG. 5 is a time chart showing another example of operation states ofvarious components during execution of the hydraulic pressure regulationcontrol; and

FIG. 6 is a time chart showing still another example of operation statesof various components during execution of the hydraulic pressureregulation control.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A control device according to an embodiment of the present inventionwill be described with reference to the drawings. As shown in FIG. 1, acontrol device 4 according to the embodiment is a drive device controlunit that controls a drive device 1. Here, the drive device 1 accordingto the embodiment is a vehicle drive device (hybrid vehicle drivedevice) that drives a vehicle (hybrid vehicle) 6 that includes both aninternal combustion engine 11 and a rotary electric machine 12 as driveforce sources for wheels 15. The control device 4 according to theembodiment will be described in detail below.

In the following description, the term “drivably coupled” means a statein which two rotary elements are coupled to each other in such a waythat allows transfer of a drive force, which includes a state in whichthe two rotary elements are coupled to each other to rotate togetherwith each other, and a state in which the two rotary elements arecoupled to each other via one or two or more transmission members insuch a way that allows transfer of a drive force. Examples of suchtransmission members include various members that transfer rotation atan equal speed or a changed speed, such as a shaft, a gear mechanism, abelt, and a chain. Here, the term “drive force” is used as a synonym for“torque”.

The term “engagement pressure” refers to a pressure at which anengagement member on one side of a friction engagement device and anengagement member on the other side of the friction engagement deviceare pressed against each other. The term “disengagement pressure” refersto a pressure at which the friction engagement device is steadilybrought into a disengaged state. The term “disengagement boundarypressure” refers to a pressure (disengagement-side slip boundarypressure) at which the friction engagement device is brought into a slipboundary state between the disengaged state and the slip engagementstate. The term “engagement boundary pressure” refers to a pressure(engagement-side slip boundary pressure) at which the frictionengagement device is brought into a slip boundary state between the slipengagement state and the direct engagement state. The term “completeengagement pressure” refers to a pressure at which the frictionengagement device is steadily brought into the direct engagement state.

1. Configuration of Drive Device

The configuration of the drive device 1 to be controlled by the controldevice 4 according to the embodiment will be described. The drive device1 according to the embodiment is formed as a drive device for a hybridvehicle of a so-called one-motor parallel type. As shown in FIG. 1, thedrive device 1 includes the rotary electric machine 12 provided on apower transfer path that connects between an input shaft I drivablycoupled to the internal combustion engine 11 and an output shaft Odrivably coupled to the wheels 15, and a speed change mechanism 13provided between the rotary electric machine 12 and the output shaft O.A first clutch CL1 is provided between the input shaft I and the rotaryelectric machine 12. As discussed later, the speed change mechanism 13includes a second clutch CL2 for shifting that is separate from thefirst clutch CL1. Thus, the drive device 1 includes the first clutchCL1, the rotary electric machine 12, and the second clutch CL2, whichare provided in the power transfer path that connects between the inputshaft I and the output shaft O and which are arranged in this order fromthe side of the internal combustion engine 11 and the input shaft I.These components are housed in a drive device case (not shown).

The internal combustion engine 11 is a motor driven by combusting fuelinside the engine to take out power. A gasoline engine, a diesel engine,or the like may be used as the internal combustion engine 11, forexample. The internal combustion engine 11 is drivably coupled to theinput shaft I so as rotate together with the input shaft I. In theexample, an output shaft, such as a crankshaft, of the internalcombustion engine 11 is drivably coupled to the input shaft I. Theinternal combustion engine 11 is drivably coupled to the rotary electricmachine 12 via the first clutch CL1.

The first clutch CL1 can release drivable coupling between the internalcombustion engine 11 and the rotary electric machine 12. The firstclutch CL1 is a clutch that selectively drivably couples the input shaftI and an intermediate shaft M and the output shaft O to each other, andfunctions as a clutch for disconnection of the internal combustionengine. A wet multi-plate clutch, a dry single-plate clutch, or the likemay be used as the first clutch CL1. In the embodiment, the first clutchCL1 corresponds to the “first friction engagement device” according tothe present invention.

The rotary electric machine 12 includes a rotor and a stator (notshown), and can function both as a motor (electric motor) that issupplied with electric power to generate power and as a generator(electric generator) that is supplied with power to generate electricpower. The rotor of the rotary electric machine 12 is drivably coupledto the intermediate shaft M so as to rotate together with theintermediate shaft M. The rotary electric machine 12 is electricallyconnected to an electricity accumulation device 28 via an inverterdevice 27. A battery, a capacitor, or the like may be used as theelectricity accumulation device 28. The rotary electric machine 12receives electric power supplied from the electricity accumulationdevice 28 for power running, or supplies electric power generated usingtorque output from the internal combustion engine 11 or an inertialforce of the vehicle 6 to the electricity accumulation device 28 toaccumulate the electric power in the electricity accumulation device 28.The intermediate shaft M is drivably coupled to the speed changemechanism 13. That is, the intermediate shaft M, which is an outputshaft (rotor output shaft) of the rotor of the rotary electric machine12, serves as an input shaft (transmission input shaft) of the speedchange mechanism 13.

In the embodiment, the speed change mechanism 13 is a stepped automatictransmission that enables switching between a plurality of shift speedswith different speed ratios. In order to provide the plurality of shiftspeeds, the speed change mechanism 13 includes a gear mechanism such asa planetary gear mechanism, and a plurality of friction engagementdevices, such as clutches and brakes, that engage and disengage rotaryelements of the gear mechanism to switch between the shift speeds. Here,the speed change mechanism 13 includes the second clutch CL2 serving asone of the plurality of friction engagement devices for shifting. In theembodiment, the second clutch CL2 is formed as a wet multi-plate clutch.The second clutch CL2 selectively drivably couples the intermediateshaft M and a transmission intermediate shaft S provided in the speedchange mechanism 13 to each other. In the embodiment, the second clutchCL2 corresponds to the “second friction engagement device” according tothe present invention. The transmission intermediate shaft S is drivablycoupled to the output shaft O via other clutches or shaft members in thespeed change mechanism 13.

The speed change mechanism 13 transfers rotation of the intermediateshaft M to the output shaft O with the rotational speed of theintermediate shaft M changed on the basis of a predetermined speed ratioset for each shift speed established in accordance with the engagementstate of the plurality of clutches etc. and with torque converted. Thetorque transferred from the speed change mechanism 13 to the outputshaft O is distributed and transferred to the two, left and right,wheels 15 via an output differential gear device 14. This allows thedrive device 1 to transfer torque of one or both of the internalcombustion engine 11 and the rotary electric machine 12 to the wheels 15to drive the vehicle 6.

In the embodiment, the drive device 1 includes an oil pump (not shown)drivably coupled to the intermediate shaft M. The oil pump functions asa hydraulic pressure source that supplies oil to various components ofthe drive device 1. The oil pump is actuated by being driven by a driveforce of one or both of the rotary electric machine 12 and the internalcombustion engine 11 to generate a hydraulic pressure. The oil from theoil pump is regulated to a predetermined hydraulic pressure by ahydraulic pressure control device 25 to be supplied to the first clutchCL1, the second clutch CL2, etc. Besides the oil pump described above,an oil pump that includes a dedicated drive motor may also be provided.

As shown in FIG. 1, a plurality of sensors Se1 to Se5 are provided invarious portions of the vehicle 6 incorporating the drive device 1. Theinput shaft rotational speed sensor Se1 is a sensor that detects therotational speed of the input shaft I. The rotational speed of the inputshaft I detected by the input shaft rotational speed sensor Se1 is equalto the rotational speed of the internal combustion engine 11. Theintermediate shaft rotational speed sensor Se2 is a sensor that detectsthe rotational speed of the intermediate shaft M. The rotational speedof the intermediate shaft M detected by the intermediate shaftrotational speed sensor Se2 is equal to the rotational speed of therotor of the rotary electric machine 12. The output shaft rotationalspeed sensor Se3 is a sensor that detects the rotational speed of theoutput shaft O. The control device 4 can also derive the vehicle speed,at which the vehicle 6 is driven, on the basis of the rotational speedof the output shaft O detected by the output shaft rotational speedsensor Se3.

The accelerator operation amount detection sensor Se4 is a sensor thatdetects the amount of operation of an accelerator pedal 17 to detect theaccelerator operation amount. The charge state detection sensor Se5 is asensor that detects the state of charge (SOC). The control device 4 canalso derive the amount of electric power accumulated in the electricityaccumulation device 28 on the basis of the SOC detected by the chargestate detection sensor Se5. Information indicating the detection resultsof the sensors Set to Se5 is output to the control device 4.

2. Configuration of Control Device

The configuration of the control device 4 according to the embodimentwill be described. As shown in FIG. 1, the control device 4 according tothe embodiment includes a drive device control unit 40. The drive devicecontrol unit 40 mainly controls the rotary electric machine 12, thefirst clutch CL1, and the speed change mechanism 13. Besides the drivedevice control unit 40, the vehicle 6 also includes an internalcombustion engine control unit 30 that mainly controls the internalcombustion engine 11.

The internal combustion engine control unit 30 and the drive devicecontrol unit 40 are configured to exchange information between eachother. Various functional sections provided in the internal combustionengine control unit 30 and the drive device control unit 40 are alsoconfigured to exchange information between each other. The internalcombustion engine control unit 30 and the drive device control unit 40are also configured to acquire information indicating the detectionresults of the sensors Se1 to Se5.

The internal combustion engine control unit 30 includes an internalcombustion engine control section 31. The internal combustion enginecontrol section 31 is a functional section that controls operation ofthe internal combustion engine 11. The internal combustion enginecontrol section 31 decides target torque and a target rotational speedfor the internal combustion engine 11 as control targets for outputtorque (internal combustion engine torque Te) and the rotational speedof the internal combustion engine 11, and drives the internal combustionengine 11 in accordance with the decided control targets. In theembodiment, the internal combustion engine control section 31 can switchcontrol for the internal combustion engine 11 between torque control androtational speed control in accordance with the travel state of thevehicle 6. In the torque control, a command for the target torque isprovided to the internal combustion engine 11 to make the internalcombustion engine torque Te coincide with (follow) the target torque. Inthe rotational speed control, a command for the target rotational speedis provided to the internal combustion engine 11 to decide output torquesuch that the rotational speed of the internal combustion engine 11coincides with the target rotational speed.

The drive device control unit 40 includes a travel mode decision section41, a required torque decision section 42, a rotary electric machinecontrol section 43, a first clutch operation control section 44, a speedchange mechanism operation control section 45, a starting controlsection 46, and a hydraulic pressure regulation control section 47.

The travel mode decision section 41 is a functional section that decidesa travel mode of the vehicle 6. The travel mode decision section 41decides the travel mode to be established by the drive device 1 on thebasis of, for example, the vehicle speed derived on the basis of theresults of detection performed by the output shaft rotational speedsensor Se3, the accelerator operation amount detected by the acceleratoroperation amount detection sensor Se4, the amount of electric poweraccumulated in the electricity accumulation device 28 derived on thebasis of the results of detection performed by the charge statedetection sensor Se5, and so forth. In this event, the travel modedecision section 41 references a mode selection map (not shown) storedin a storage device such as a memory.

In the example, examples of the travel mode that can be selected by thetravel mode decision section 41 include an electric power travel mode, aparallel travel mode, and a slip travel mode (including a first sliptravel mode and a second slip travel mode). In the electric power travelmode, the first clutch CL1 is brought into the disengaged state, and thevehicle 6 is driven by only the output torque (rotary electric machinetorque Tm) of the rotary electric machine 12. In the parallel travelmode, both the first clutch CL1 and the second clutch CL2 are broughtinto the direct engagement state, and the vehicle 6 is driven by atleast the internal combustion engine torque Te.

In the first slip travel mode, both the first clutch CL1 and the secondclutch CL2 are brought into the slip engagement state, and the vehicle 6is driven with at least the internal combustion engine torque Tetransferred to the wheels 15. In the second slip travel mode, one of thefirst clutch CL1 and the second clutch CL2 (in the example, the firstclutch CL1) is brought into the direct engagement state and the other(in the example, the second clutch CL2) is brought into the slipengagement state, and the vehicle 6 is driven with at least the internalcombustion engine torque Te transferred to the wheels 15. In theparallel travel mode and the slip travel mode, the rotary electricmachine 12 outputs positive rotary electric machine torque Tm (>0) tosupplement a drive force provided by the internal combustion enginetorque Te, or outputs negative rotary electric machine torque Tm (<0) togenerate electric power using the internal combustion engine torque Te,as necessary. The modes described here are merely illustrative, and aconfiguration including various other modes may also be adopted.

The required torque decision section 42 is a functional section thatdecides vehicle required torque Td required to drive the vehicle 6. Therequired torque decision section 42 decides the vehicle required torqueTd, for example by referencing a predetermined map (not shown), on thebasis of the vehicle speed derived on the basis of the results ofdetection performed by the output shaft rotational speed sensor Se3 andthe accelerator operation amount detected by the accelerator operationamount detection sensor Se4. In the embodiment, the vehicle requiredtorque Td corresponds to the “required drive force” according to thepresent invention. The decided vehicle required torque Td is output tothe internal combustion engine control section 31, the rotary electricmachine control section 43, the hydraulic pressure regulation controlsection 47, etc.

The rotary electric machine control section 43 is a functional sectionthat controls operation of the rotary electric machine 12. The rotaryelectric machine control section 43 decides target torque and a targetrotational speed for the rotary electric machine 12 as control targetsfor the rotary electric machine torque Tm and the rotational speed ofthe rotary electric machine 12, and drives the rotary electric machine12 in accordance with the decided control targets. In the embodiment,the rotary electric machine control section 43 can switch control forthe rotary electric machine 12 between torque control and rotationalspeed control in accordance with the travel state of the vehicle 6.

The rotary electric machine control section 43 includes a target torquedecision section 43 a and a rotational speed control section 43 b inorder to enable execution of the torque control and the rotational speedcontrol. The target torque decision section 43 a is a functional sectionthat decides target torque Tmf for the rotary electric machine 12. Therotary electric machine control section 43 can provide a command for thetarget torque Tmf decided by the target torque decision section 43 a tothe rotary electric machine 12 to execute torque control for the rotaryelectric machine 12 in a feedforward manner such that the rotaryelectric machine torque Tm coincides with the target torque Tmf. Therotational speed control section 43 b is a functional section thatexecutes rotational speed control in which a command for a targetrotational speed Nmt is provided to the rotary electric machine 12 todecide output torque such that the rotational speed of the rotaryelectric machine 12 coincides with the target rotational speed Nmt. Inthe embodiment, the rotational speed control for the rotary electricmachine 12 corresponds to the “rotational speed feedback control” andthe “rotational state control” according to the present invention. Therotary electric machine control section 43 can also control therotational speed of the rotary electric machine 12 in a feedback mannerwhile controlling the rotary electric machine torque Tm in a feedforwardmanner through cooperation between the target torque decision section 43a and the rotational speed control section 43 b.

The first clutch operation control section 44 is a functional sectionthat controls operation of the first clutch CL1. The first clutchoperation control section 44 controls operation of the first clutch CL1by controlling the hydraulic pressure supplied to the first clutch CL1via the hydraulic pressure control device 25 to control the engagementpressure of the first clutch CL1. For example, the first clutchoperation control section 44 outputs a hydraulic pressure command valuefor the first clutch CL1, and brings the first clutch CL1 into thedisengaged state by controlling the hydraulic pressure to be supplied tothe first clutch CL1 to be less than the disengagement boundary pressurevia the hydraulic pressure control device 25. The first clutch operationcontrol section 44 brings the first clutch CL1 into the directengagement state by controlling the hydraulic pressure to be supplied tothe first clutch CL1 to be equal to or more than the engagement boundarypressure via the hydraulic pressure control device 25. The first clutchoperation control section 44 brings the first clutch CL1 into the slipengagement state by controlling the hydraulic pressure to be supplied tothe first clutch CL1 to a slip engagement pressure that is equal to ormore than the disengagement boundary pressure and that is less than theengagement boundary pressure via the hydraulic pressure control device25.

With the first clutch CL1 in the slip engagement state, a drive force istransferred between the input shaft I and the intermediate shaft M withthe input shaft I and the intermediate shaft M rotatable relative toeach other. The magnitude of torque that can be transferred by the firstclutch CL1 in the direct engagement state or the slip engagement stateis decided in accordance with the engagement pressure of the firstclutch CL1 at the time point. The magnitude of torque at this time isdefined as “transfer torque capacity Tc1” of the first clutch CL1. Inthe embodiment, the first clutch operation control section 44 cancontinuously control increase and decrease in engagement pressure andtransfer torque capacity Tc1 by continuously controlling the magnitudesof the amount of oil and the hydraulic pressure to be supplied to thefirst clutch CL1 in accordance with the hydraulic pressure command valuefor the first clutch CL1 through a proportional solenoid or the like.The direction of torque transferred via the first clutch CL1 with thefirst clutch CL1 in the slip engagement state is decided in accordancewith the direction of relative rotation between the input shaft I andthe intermediate shaft M. That is, in the case where the rotationalspeed of the input shaft I is higher than the rotational speed of theintermediate shaft M, torque is transferred from the input shaft I sideto the intermediate shaft M side via the first clutch CL1. In the casewhere the rotational speed of the input shaft I is lower than therotational speed of the intermediate shaft M, torque is transferred fromthe intermediate shaft M side to the input shaft I side via the firstclutch CL1.

In the embodiment, in addition, the first clutch operation controlsection 44 can switch control for the first clutch CL1 between torquecapacity control and rotational speed control in accordance with thetravel state of the vehicle 6. In the torque capacity control, thetransfer torque capacity Tc1 of the first clutch CL1 is caused tocoincide with a predetermined target transfer torque capacity. In therotational speed control, the hydraulic pressure command value for thefirst clutch CL1 or the target transfer torque capacity for the firstclutch CL1 is decided such that a rotational speed difference betweenthe rotational speed of a rotary member (in the example, the input shaftI) coupled to one engagement member of the first clutch CL1 and therotational speed of a rotary member (in the example, the intermediateshaft M) coupled to the other engagement member coincides with apredetermined target rotational speed difference. In the rotationalspeed control for the first clutch CL1, the rotational speed of theinput shaft I can be controlled so as to coincide with the predeterminedtarget rotational speed by causing the rotational speed differencedescribed above to coincide with the predetermined target rotationalspeed difference with the rotational speed of the intermediate shaft Mcontrolled to a predetermined value, for example.

The speed change mechanism operation control section 45 is a functionalsection that controls operation of the speed change mechanism 13. Thespeed change mechanism operation control section 45 decides a targetshift speed on the basis of the accelerator operation amount and thevehicle speed, and controls the speed change mechanism 13 so as toestablish the decided target shift speed. In this event, the speedchange mechanism operation control section 45 references a speed changemap (not shown) stored in a storage device such as a memory. The speedchange map is a map in which schedules for shifting are set on the basisof the accelerator operation amount and the vehicle speed. The speedchange mechanism operation control section 45 controls the hydraulicpressure to be supplied to a predetermined clutch, brake, or the likeprovided in the speed change mechanism 13 on the basis of the decidedtarget shift speed to establish the target shift speed.

As described above, the speed change mechanism 13 includes the secondclutch CL2 for shifting. The second clutch CL2 establishes a first speedthrough cooperation with a predetermined brake also provided in thespeed change mechanism 13, for example. As a matter of course, thesecond clutch CL2 is also controlled by the speed change mechanismoperation control section 45. Here, a functional section that controlsoperation of the second clutch CL2 is specifically referred to as asecond clutch operation control section 45 a. The second clutchoperation control section 45 a controls operation of the second clutchCL2 by controlling the hydraulic pressure supplied to the second clutchCL2 via the hydraulic pressure control device 25 to control theengagement pressure of the second clutch CL2. Operation control for thesecond clutch CL2 performed by the second clutch operation controlsection 45 a is basically the same as operation control for the firstclutch CL1 performed by the first clutch operation control section 44except for the target to be controlled and some relevant matters.

The starting control section 46 is a functional section that executesstarting control. The starting control section 46 executes the startingcontrol in the case where a starting operation performed by a driver issensed while the vehicle 6 is stationary, for example. Here, the term“starting operation” refers to an operation performed by the driver ofthe vehicle 6 with an intention to start the vehicle. In the example,the starting operation is defined as an operation to release a brakepedal (not shown), which may allow the vehicle 6 to start creeping.Alternatively, an operation to depress the accelerator pedal 17 may besensed as the “starting operation”. The starting control section 46executes the starting control to appropriately start the vehicle 6 bycooperatively controlling the internal combustion engine control section31, the rotary electric machine control section 43, the first clutchoperation control section 44, the second clutch operation controlsection 45 a, and so forth.

In the embodiment, the starting control section 46 executes the startingcontrol during a period for which the vehicle 6 is in a predeterminedlow vehicle speed state. Here, the term “low vehicle speed state” refersto a state in which the rotational speed of the input shaft I (internalcombustion engine 11) estimated in the case where it is assumed thatboth the first clutch CL1 and the second clutch CL2 are in the directengagement state with the first speed established in the speed changemechanism 13 is equal to or less than a low vehicle-speed determinationthreshold Th1 (not shown). It is necessary that the internal combustionengine 11, which is drivably coupled to the input shaft I so as torotate together with the input shaft I, should rotate at a certain speedor more in order to output predetermined internal combustion enginetorque Te to continue self-sustained operation. It is also necessarythat the internal combustion engine 11 should rotate at a certain speedor more from the viewpoint of suppressing occurrence of a muffled soundand vibration. Therefore, in the example, the low vehicle-speeddetermination threshold Th1 is set in consideration of such factors.

In the embodiment, the starting control section 46 establishes, as thetravel mode of the vehicle 6, the first slip travel mode and the secondslip travel mode sequentially in this order during the starting control.That is, in the starting control, the starting control section 46 firstbrings both the first clutch CL1 and the second clutch CL2 into the slipengagement state. Then, the starting control section 46 causes theinternal combustion engine torque Te to be transferred to the wheels 15in the first slip travel mode with both the first clutch CL1 and thesecond clutch CL2 in the slip engagement state to start the vehicle 6.In this event, the starting control section 46 causes the rotationalspeed control section 43 b to execute rotational speed control for therotary electric machine 12 to perform feedback control on the rotationalspeed of the rotary electric machine 12 so as to coincide with thedecided target rotational speed Nmt.

In the embodiment, the target rotational speed Nmt for the rotaryelectric machine 12 during the starting control is set to a value thatis larger than the rotational speed of the intermediate shaft M matchingthe rotational speed of the output shaft O in the case where it isassumed that the first speed is established in the speed changemechanism 13 and that is at least smaller than the rotational speed ofthe internal combustion engine 11 continuing its self-sustainedoperation. In deciding the target rotational speed Nmt for the rotaryelectric machine 12, rated power consumption or actual power consumptionof electrically-driven accessories provided in the vehicle 6 (such as acompressor of an in-vehicle air conditioner and lamps, for example) maybe taken into consideration. Alternatively, the amount of generated heatbased on the rotational speed difference of each of the first clutch CL1and the second clutch CL2 etc. may be taken into consideration. Stillalternatively, the rotational speed of an oil pump (not shown) that cansecure a supplied hydraulic pressure necessary for all thehydraulically-driven friction engagement devices (including the firstclutch CL1 and the second clutch CL2) provided in the drive device 1 maybe taken into consideration.

In the example, the target rotational speed Nmt for the rotary electricmachine 12 in the first slip travel mode is set in accordance with thevehicle speed (see FIG. 4). In the illustrated example, the targetrotational speed Nmt is maintained at a constant value when the vehicle6 is stationary. After the vehicle speed starts rising, the targetrotational speed Nmt for the rotary electric machine 12 also rises at aconstant time variation rate in accordance with the rotational speed ofthe transmission intermediate shaft S which is proportional to thevehicle speed. Then, the rotational speed of the rotary electric machine12 rises at a constant time variation rate so as to follow the targetrotational speed Nmt described above. Torque (inertia torque) forvarying the rotational speed of the rotary electric machine 12 towardthe target rotational speed Nmt at each time point is referred to hereinas “rotation-varying torque Tmi”.

In the first slip travel mode during the starting control, the internalcombustion engine control section 31 performs torque control for theinternal combustion engine 11, and the first clutch operation controlsection 44 performs rotational speed control for the first clutch CL1which is in the slip engagement state until the direct engagement stateis established with the internal combustion engine 11 and the rotaryelectric machine 12 synchronized with each other. The rotational speedcontrol section 43 b executes rotational speed control for the rotaryelectric machine 12 as described above, and the hydraulic pressureregulation control section 47 executes hydraulic pressure regulationcontrol for the second clutch CL2. The hydraulic pressure regulationcontrol performed by the hydraulic pressure regulation control section47 will be discussed in detail later.

In the embodiment, the internal combustion engine control section 31sets target torque for a period during the starting control to a valueobtained by subtracting target torque for the rotary electric machine 12from the vehicle required torque Td, and performs torque control for theinternal combustion engine 11 such that the internal combustion enginetorque Te coincides with the set target torque. In the case where therotary electric machine 12 generates electric power, the internalcombustion engine control section 31 sets target torque for a periodduring the starting control to a value obtained by adding the vehiclerequired torque Td and torque for electric power generation (electricpower generation torque), and performs torque control for the internalcombustion engine 11 such that the internal combustion engine torque Tecoincides with the set target torque.

With the first clutch CL1 in the slip engagement state, the first clutchoperation control section 44 sets a target rotational speed for theinput shaft I (internal combustion engine 11), and performs rotationalspeed control in which the transfer torque capacity Tc1 of the firstclutch CL1 is controlled such that the rotational speed (a type ofrotational state) of the input shaft I (internal combustion engine 11)coincides with the set target rotational speed. In the rotational speedcontrol for the first clutch CL1, the internal combustion engine torqueTe is transferred as it is to the rotary electric machine 12 side. Alsoafter the first clutch CL1 is brought into the direct engagement state,the internal combustion engine torque Te is transferred as it is to therotary electric machine 12 side. The second clutch CL2 is in the slipengagement state, and is basically subjected to torque capacity controlso as to transfer torque matching the vehicle required torque Td.

In the embodiment, when the rotational speed of the rotary electricmachine 12 rises to coincide with the rotational speed of the internalcombustion engine 11 in the course of time, the first clutch operationcontrol section 44 brings the first clutch CL1 into the directengagement state with the second clutch CL2 maintained in the slipengagement state, and causes the internal combustion engine torque Te tobe transferred to the wheels 15 to drive the vehicle 6 in the secondslip travel mode. Also in the second slip travel mode, the startingcontrol section 46 causes the rotational speed control section 43 b toexecute rotational speed control for the rotary electric machine 12 toperform feedback control on the rotational speed of the rotary electricmachine 12 so as to coincide with the decided target rotational speedNmt. In the example, the target rotational speed Nmt for the rotaryelectric machine 12 in the second slip travel mode rises at a constanttime variation rate that is lower than the time variation rate of therotational speed of the transmission intermediate shaft S so as togradually reduce the difference in rotational speed between thetransmission intermediate shaft S and the rotary electric machine 12(see FIG. 4).

In the second slip travel mode during the starting control, the internalcombustion engine control section 31 continues the torque control forthe internal combustion engine 11, and the internal combustion enginetorque Te is transferred as it is to the rotary electric machine 12 sidevia the first clutch CL1 in the direct engagement state. The rotationalspeed control section 43 b continues to execute the rotational speedcontrol for the rotary electric machine 12. The hydraulic pressureregulation control section 47 continues to execute the hydraulicpressure regulation control for the second clutch CL2. These controlsare the same as those in the first slip travel mode. When the rotationalspeed of the transmission intermediate shaft S rises to coincide withthe rotational speed of the rotary electric machine 12 in the course oftime, the second clutch operation control section 45 a brings the secondclutch CL2 into the direct engagement state. After the second clutch CL2is brought into the direct engagement state, the rotational speed of therotary electric machine 12 is defined uniquely in accordance with therotational speed of the wheels 15, which does not allow to maintain therotational speed control any more. In this case, the rotary electricmachine control section 43 performs torque control for the rotaryelectric machine 12 so as to output the target torque Tmf decided by thetarget torque decision section 43 a.

In the embodiment, in this way, during the starting control, the secondclutch CL2 is basically brought into the slip engagement state, andcontrolled such that the transfer torque capacity Tc2 becomes torquematching the vehicle required torque Td. This makes it possible toappropriately drive the vehicle 6 with the vehicle required torque Tdfulfilled while driving the internal combustion engine 11 at arotational speed at which self-sustained operation can be stablycontinued. When the vehicle speed becomes sufficiently high after thevehicle 6 starts, the second clutch CL2 is transitioned from the slipengagement state to the direct engagement state to start travel in theparallel travel mode.

The target torque Tmf for the rotary electric machine 12 during thestarting control is a value obtained by subtracting the target torquefor the internal combustion engine 11 from the vehicle required torqueTd. The target torque Tmf for the rotary electric machine 12 ismaintained also after the starting control is terminated (during travelin the parallel travel mode).

During the starting control, in an ideal state in which the controlsdiscussed above are executed precisely as discussed above, as shown in(a) of FIG. 2, torque transferred to the rotary electric machine 12 viathe input shaft I and the first clutch CL1 perfectly coincides with thetarget torque for the internal combustion engine 11 (which is referredto here as “Te0”), and torque transferred to the output shaft O via thesecond clutch CL2 in the slip engagement state perfectly coincides withthe vehicle required torque Td (which is referred to here as “Td0”). Inthis case, the target torque Tmf (which is referred to here as “Tm0”)for the rotary electric machine 12 during the rotational speed controlfor the rotary electric machine 12 performed along with the startingcontrol perfectly coincides with a value obtained by subtracting thetarget torque Te0 for the internal combustion engine 11 from the vehiclerequired torque Td0 (Tm0=Td0−Te0). Accordingly, even if the startingcontrol is terminated and the torque control for the rotary electricmachine 12 is started, the target torque Tmf for the rotary electricmachine 12 is maintained at Tm0 around the transition of the secondclutch CL2 from the slip engagement state to the direct engagementstate, and no torque fluctuations are transferred to the output shaft O.Here, in order to simplify the model for ease of description, the speedratio of the first shift speed is set to “1”.

Practically, however, as shown in (b) of FIG. 2, torque (which isreferred to here as “Te1”) of the internal combustion engine 11transferred to the rotary electric machine 12 via the input shaft I andthe first clutch CL1 does not perfectly coincide with the target torqueTe0 for the internal combustion engine 11, and there may be apredetermined difference ΔTe from the target torque Te0 (Te1=Te0+ΔTe).In this case, torque (which is referred to here as “Tm1”) of the rotaryelectric machine 12 subjected to the rotational speed control issubtracted from the target torque Tm0 to cancel the difference ΔTe ofthe internal combustion engine torque Te from the target torque Te0(Tm1=Tm0−ΔTe). As a result, torque transferred to the output shaft O viathe second clutch CL2 in the slip engagement state coincides with thevehicle required torque Td0.

Meanwhile, when the starting control is terminated and the second clutchCL2 is brought into the direct engagement state, and the torque controlfor the rotary electric machine 12 is started in the parallel travelmode, torque of the rotary electric machine 12 is momentarily andforcibly returned to the target torque Tm0. As a result, torque (whichis referred to here as “Td1”) transferred to the output shaft O via thesecond clutch CL2 which has been brought into the direct engagementstate becomes a value obtained by adding the internal combustion enginetorque Te1 (=Te0+ΔTe) and the target torque Tm0 (=Td0−Te0) for therotary electric machine 12 to each other (Td1=Td0+ΔTe). In this way,when the starting control is terminated and the torque control for therotary electric machine 12 is started (in switching from the second sliptravel mode to the parallel travel mode), torque transferred to theoutput shaft O via the second clutch CL2 is varied from Td0 to Td1(=Td0+ΔTe) because of an error (difference ΔTe) in torque actuallyoutput from the internal combustion engine 11 around the transition ofthe second clutch CL2 from the slip engagement state to the directengagement state. That is, a torque difference with a magnitudecorresponding to the difference ΔTe of the internal combustion enginetorque Te from the target torque Te0 is caused in torque transferred tothe output shaft O. Occurrence of such a torque difference may cause theoccupants of the vehicle 6 to feel a shock, and thus is not preferable.

Thus, in order to address such an issue, the embodiment includes thehydraulic pressure regulation control section 47 which executes thehydraulic pressure regulation control concurrently with the startingcontrol. The hydraulic pressure regulation control executed by thehydraulic pressure regulation control section 47 will be described indetail below with reference to FIGS. 2 to 4.

3. Content of Hydraulic Pressure Regulation Control

The content of the hydraulic pressure regulation control according tothe embodiment will be described. The hydraulic pressure regulationcontrol is started at the same time as the starting control is started.In the example, the hydraulic pressure regulation control is executedwith the internal combustion engine torque Te transferred to the wheels15 while executing the rotational speed control for the first clutch CL1with both the first clutch CL1 and the second clutch CL2 in the slipengagement state. More specifically, the hydraulic pressure regulationcontrol is executed in a period after the second clutch CL2 is broughtinto the slip engagement state to start the vehicle 6 and before thesecond clutch CL2 is transitioned from the slip engagement state to thedirect engagement state. In the embodiment, the hydraulic pressureregulation control is executed continuously during a period after thesecond clutch CL2 is brought into the slip engagement state and beforethe second clutch CL2 is transitioned from the slip engagement state tothe direct engagement state.

In the hydraulic pressure regulation control, the basic concept of whichis shown in (c) of FIG. 2, the target torque for the rotary electricmachine 12 is continuously (gradually) varied from Tm1 (=Tm0−ΔTe) towardTm0, and torque transferred to the output shaft O via the second clutchCL2 is continuously varied from Td0 toward Td1 (=Td0+ΔTe).

FIG. 3 is a block diagram showing the configuration of the rotaryelectric machine control section 43 (including the target torquedecision section 43 a and the rotational speed control section 43 b) andthe hydraulic pressure regulation control section 47. An internalcombustion engine torque command Ce and the vehicle required torque Tdare input to the target torque decision section 43 a. In the embodiment,the internal combustion engine torque command Ce is a command value fortarget torque in the torque control for the internal combustion engine11, and is decided by the internal combustion engine control section 31.The vehicle required torque Td is decided by the required torquedecision section 42. The target torque decision section 43 a includes atarget torque computing unit 51. The target torque computing unit 51performs computation to subtract the internal combustion engine torquecommand Ce from the vehicle required torque Td to output the difference(Td−Ce) obtained as the results of such computation as the target torqueTmf.

With the first clutch CL1 subjected to the rotational speed control, theinternal combustion engine torque Te matching the internal combustionengine torque command Ce is transferred as it is to the rotary electricmachine 12 side via the input shaft I and the first clutch CL1. That is,the internal combustion engine torque Te matching the internalcombustion engine torque command Ce that is not affected by an error intransfer torque capacity Tc1 of the first clutch CL1 is transferred tothe rotary electric machine 12 side, Thus, the target torque decisionsection 43 a decides the target torque Tmf for the rotary electricmachine 12 on the basis of the difference between the vehicle requiredtorque Td for driving the wheels 15 and the internal combustion enginetorque command Ce serving as a command value for torque transferred tothe rotary electric machine 12 via the input shaft I. The thuscalculated target torque Tmf is a feedforward torque command decided ina feedforward manner.

The target rotational speed Nmt and an actual rotational speed Nmr ofthe rotary electric machine 12 are input to the rotational speed controlsection 43 b. The target rotational speed Nmt for the rotary electricmachine 12 is set as described above. The actual rotational speed Nmr ofthe rotary electric machine 12 is detected by the intermediate shaftrotational speed sensor Se2. The target rotational speed Nmt and theactual rotational speed Nmr are input to a subtractor 61, which outputsthe resulting difference (Nmr−Nmt) between the actual rotational speedNmr and the target rotational speed Nmt as a rotational speed deviationΔNm. The rotational speed deviation ΔNm is input to a correction torquecomputing unit 52.

The correction torque computing unit 52 calculates correction torque Tmbthat brings the rotational speed deviation ΔNm to zero on the basis ofthe input rotational speed deviation ΔNm to output the calculatedcorrection torque Tmb. The correction torque computing unit 52 may beconfigured to perform computation in which one or more of proportionalcontrol, integral control, and differential control known in the art areappropriately combined with each other. In the embodiment, thecorrection torque computing unit 52 is configured to perform computationthrough proportional-integral control (PI control). The correctiontorque computing unit 52 outputs the results of such computation as thecorrection torque Tmb for the target torque Tmf. The thus calculatedcorrection torque Tmb is a feedback torque command decided in a feedbackmanner. The correction torque Tmb is torque of the rotary electricmachine 12 necessary to cause the actual rotational speed Nmr of therotary electric machine 12 during the rotational speed control tocoincide with the target rotational speed Nmt (to cause the rotationalspeed deviation ΔNm to become zero).

The target torque Tmf calculated by the target torque computing unit 51and the correction torque Tmb calculated by the correction torquecomputing unit 52 are input to an adder 62, which outputs the resultingsum (Tmf+Tmb) of the target torque Tmf and the correction torque Tmb asa rotary electric machine torque command Cm from the rotary electricmachine control section 43. The rotary electric machine control section43 controls operation of the rotary electric machine 12 on the basis ofthe rotary electric machine torque command Cm.

At least the vehicle required torque Td is input to the hydraulicpressure regulation control section 47. The hydraulic pressureregulation control section 47 includes a target torque capacitycomputing unit 53. The target torque capacity computing unit 53calculates a target torque capacity Tcf matching the vehicle requiredtorque Td on the basis of the input vehicle required torque Td to outputthe calculated target torque capacity Tcf. The thus calculated targettorque capacity Tcf is a feedforward torque capacity command decided ina feedforward manner. The target torque capacity Tcf is calculated, asit is, as a second clutch torque capacity command Cc2. The configurationfor a case where operation of the second clutch CL2 is controlled on thebasis of a second clutch hydraulic pressure command Pc2 matching thesecond clutch torque capacity command Cc2 is a premise for the presentinvention, and is known in the art.

In the embodiment, the correction torque Tmb calculated by thecorrection torque computing unit 52 and the actual rotational speed Nmrof the rotary electric machine 12 detected by the intermediate shaftrotational speed sensor Set are further input to the hydraulic pressureregulation control section 47. The hydraulic pressure regulation controlsection 47 also includes a rotation-varying torque computing unit 54, atorque capacity correction amount computing unit 55, and a hydraulicpressure command generator 56. The rotation-varying torque computingunit 54 performs computation to calculate the rotation-varying torqueTmi for the rotor of the rotary electric machine 12 on the basis of theinput actual rotational speed Nmr. Here, the rotation-varying torque Tmiis torque (inertia torque) for varying the actual rotational speed Nmrtoward the target rotational speed Nmt in the rotational speed controlfor the rotary electric machine 12. The rotation-varying torquecomputing unit 54 multiplies inertia Jm of the rotor of the rotaryelectric machine 12 and a time differential of the actual rotationalspeed Nmr with each other to output the resulting product (Jm·(dNmr/dt))as the rotation-varying torque Tmi.

The correction torque Tmb calculated by the correction torque computingunit 52 and the rotation-varying torque Tmi calculated by therotation-varying torque computing unit 54 are input to a subtractor 63,which outputs the resulting difference (Tmb−Tmi) between the correctiontorque Tmb and the rotation-varying torque Tmi as a torque error ΔT. Thetorque error ΔT is caused by an error in internal combustion enginetorque Te actually output from the internal combustion engine 11, andmay be referred to also as “correction torque Tmb calculated with theexclusion of an amount corresponding to the rotation-varying torqueTmi”. With the actual rotational speed Nmr of the rotary electricmachine 12 already coinciding with the target rotational speed Nmt, therotation-varying torque Tmi is zero, and the torque error ΔT coincideswith the correction torque Tmb. The torque error ΔT is input to thetorque capacity correction amount computing unit 55.

The torque capacity correction amount computing unit 55 calculates atorque capacity correction amount Tcb on the basis of the input torqueerror ΔT. In the embodiment, the torque capacity correction amountcomputing unit 55 calculates such a torque capacity correction amountTcb that causes the torque error ΔT to approach zero to output thecalculated torque capacity correction amount Tcb. The torque capacitycorrection amount computing unit 55 may be configured to performcomputation in which one or more of proportional control, integralcontrol, and differential control known in the art are appropriatelycombined with each other. In the embodiment, the torque capacitycorrection amount computing unit 55 is configured to perform computationthrough integral control (I control). That is, the torque capacitycorrection amount computing unit 55 calculates the torque capacitycorrection amount Tcb on the basis of a value computed by integratingthe torque error ΔT over time. The torque capacity correction amountcomputing unit 55 outputs the results of such computation as the torquecapacity correction amount Tcb for the target torque capacity Tcf. Thethus calculated torque capacity correction amount Tcb is a feedbacktorque capacity command decided in a feedback manner.

The target torque capacity Tcf calculated by the target torque capacitycomputing unit 53 and the torque capacity correction amount Tcbcalculated by the torque capacity correction amount computing unit 55are input to a subtractor 64, which calculates the difference (Tcf−Tcb)obtained by subtracting the torque capacity correction amount Tcb fromthe target torque capacity Tcf as the second clutch torque capacitycommand Cc2. The second clutch torque capacity command Cc2 correspondsto the target transfer torque capacity for the second clutch CL2according to the embodiment.

The hydraulic pressure command generator 56 generates the second clutchhydraulic pressure command Pc2, which is a command value for thehydraulic pressure to be supplied to the second clutch CL2, on the basisof the calculated second clutch torque capacity command Cc2. Thegenerated second clutch hydraulic pressure command Pc2 is output fromthe hydraulic pressure regulation control section 47 to the hydraulicpressure control device 25. The hydraulic pressure control device 25supplies a hydraulic pressure matching the second clutch hydraulicpressure command Pc2 to the second clutch CL2.

In the embodiment, in this way, the rotational speed control for therotary electric machine 12 is executed with the rotational speed controlfor the second clutch CL2 in the slip engagement state executed, and thehydraulic pressure to be supplied to the second clutch CL2 is controlledon the basis of the torque error ΔT (including the correction torqueTmb) caused in the rotational speed control for the rotary electricmachine 12 through the hydraulic pressure regulation control executedcontinuously during a period after the second clutch CL2 is brought intothe slip engagement state and before the second clutch CL2 istransitioned from the slip engagement state to the direct engagementstate. Specifically, the hydraulic pressure regulation control section47 includes the torque capacity correction amount computing unit 55, anddecides such a torque capacity correction amount Tcb that brings thetorque error ΔT (including the correction torque Tmb) caused in therotational speed control for the rotary electric machine 12 to zero whenthe second clutch CL2 which has been in the slip engagement state istransitioned to the direct engagement state. In the embodiment, inaddition, the hydraulic pressure regulation control section 47 decidesthe second clutch torque capacity command Cc2 by subtracting the decidedtorque capacity correction amount Tcb from the target torque capacityTcf calculated by the target torque capacity computing unit 53 alsoprovided in the hydraulic pressure regulation control section 47. Thehydraulic pressure regulation control section 47 generates the secondclutch hydraulic pressure command Pc2 on the basis of the second clutchtorque capacity command Cc2, and controls the transfer torque capacityTc2 of the second clutch CL2 on the basis of the second clutch hydraulicpressure command Pc2.

By adopting such a configuration, even if a certain amount of error iscaused in the actual internal combustion engine torque Te, the torqueerror ΔT (correction torque Tmb) caused by the error can be continuously(gradually) reduced. Moreover, the torque error ΔT (correction torqueTmb) can be caused to sufficiently approach zero at the time point whenthe second clutch CL2 is transitioned from the slip engagement state tothe direct engagement state. Hence, a torque difference that occurs whenthe second clutch CL2 is transitioned from the slip engagement state tothe direct engagement state can be suppressed at the time of modeswitching from the second slip travel mode to the parallel travel mode.Thus, it is possible to avoid the possibility that the occupants of thevehicle 6 feel a shock as much as possible.

In addition, the hydraulic pressure regulation control section 47includes the rotation-varying torque computing unit 54 and thesubtractor 63, and executes the hydraulic pressure regulation control onthe basis of the correction torque Tmb (that is, the torque error ΔTdiscussed above) calculated with the exclusion of an amountcorresponding to the rotation-varying torque Tmi for varying the actualrotational speed Nmr of the rotary electric machine 12 toward the targetrotational speed Nmt. By adopting such a configuration in the hydraulicpressure regulation control, the second clutch torque capacity commandCc2 and the second clutch hydraulic pressure command Pc2 matching thesecond clutch torque capacity command Cc2 can be decided appropriatelyin consideration of only a steady error due to an error in internalcombustion engine torque Te, which allows to effectively suppressoccurrence of a torque difference. Such a configuration is particularlyeffective in a configuration in which the target rotational speed Nmt inthe rotational speed control for the rotary electric machine 12 isvaried over time as in a period at and after time T02 in the embodimentand it is necessary to output the rotation-varying torque Tmi matchingthe target rotational speed Nmt.

4. Specific Example

A specific example of the starting control and the hydraulic pressureregulation control according to the embodiment will be described withreference to the time chart of FIG. 4. The example assumes a situationwhere switching is made from a state in which electric power generationis performed while the vehicle 6 is stationary to the first slip travelmode, then to the second slip travel mode, and finally to the paralleltravel mode.

When a starting operation performed by the driver of the vehicle 6 issensed at time T01 with the rotary electric machine 12 performingelectric power generation using the internal combustion engine torque Tewhile the vehicle 6 is stationary, the starting control is started toestablish the first slip travel mode. In the first slip travel mode, theinternal combustion engine torque Te is transferred to the wheels 15with both the first clutch CL1 and the second clutch CL2 in the slipengagement state. At time T01, the internal combustion engine controlsection 31 starts the torque control for the internal combustion engine11, and the first clutch operation control section 44 starts therotational speed control for the first clutch CL1. Here, in therotational speed control for the first clutch CL1, the transfer torquecapacity Tc1 of the first clutch CL1 is controlled so as to cause therotational speed of the input shaft I to coincide with the targetrotational speed in the example. In the rotational speed control for thefirst clutch CL1, the internal combustion engine torque Te istransferred as it is to the rotary electric machine 12 side. At timeT01, in addition, the rotational speed control section 43 b starts therotational speed control for the rotary electric machine 12.

In the embodiment, the hydraulic pressure regulation control has beenstarted at the same time as the starting control is started. That is,the hydraulic pressure regulation control has been executed since beforethe first clutch CL1 is brought into the direct engagement state. In theembodiment, the first clutch CL1 is subjected to the rotational speedcontrol, and the internal combustion engine torque Te is transferred asit is to the rotary electric machine 12 side. Thus, the hydraulicpressure regulation control has been started immediately at time T01 atwhich the first slip travel mode is established.

In the illustrated example, the target rotational speed for the rotaryelectric machine 12 in the first slip travel mode is set in accordancewith the vehicle speed. That is, the target rotational speed for therotary electric machine 12 is maintained at a constant value when thevehicle is stationary, and at and after time T02 at which the vehiclespeed starts rising, the target rotational speed also rises inaccordance with the rotational speed of the transmission intermediateshaft S. When the rotational speed of the rotary electric machine 12 andthe intermediate shaft M rises, and the difference in rotational speedbetween the two engagement members (on both sides of the first clutchCL1) to be engaged with each other by the first clutch CL1 (which isequal to the difference in rotational speed between the rotary electricmachine 12 and the internal combustion engine 11 in the example) becomesequal to or less than a predetermined first synchronizationdetermination threshold TH2 at time T03 in the course of time, the firstclutch operation control section 44 determines that the first clutch CL1has been brought from the slip engagement state into the directengagement state. After it is determined that the first clutch CL1 hasbeen transitioned to the direct engagement state, the first clutchoperation control section 44 gradually raises a hydraulic pressure to besupplied to the first clutch CL1, and raises the supplied hydraulicpressure stepwise to the complete engagement pressure at time T04, atwhich a predetermined time has elapsed, to bring the first clutch CL1into the direct engagement state.

Consequently, mode switching is made from the first slip travel mode tothe second slip travel mode. Also in the second slip travel mode,however, the torque control for the internal combustion engine 11 andthe rotational speed control for the rotary electric machine 12 arecontinuously executed. In addition, the hydraulic pressure regulationcontrol for the second clutch CL2 is also continuously executed. Thedetails of the hydraulic pressure regulation control are as discussedabove. FIG. 4 shows how the torque capacity correction amount Tcb forthe target torque capacity Tcf for the second clutch CL2 isappropriately increased and decreased such that the correction torqueTmb for the target torque Tmf for the rotary electric machine 12 isgradually reduced toward zero during a period since time T01 at whichthe starting control is started until time T05 at which the secondclutch CL2 is transitioned from the slip engagement state to the directengagement state.

When the rotational speed of the transmission intermediate shaft S risesalong with a rise in vehicle speed and the difference in rotationalspeed between the two engagement members on both sides of the secondclutch CL2 (which is equal to the difference in rotational speed betweenthe rotary electric machine 12 and the intermediate shaft M and thetransmission intermediate shaft S in the example) becomes equal to orless than a predetermined second synchronization determination thresholdTh3 at time T05 in the course of time, the second clutch operationcontrol section 45 a determines that the second clutch CL2 has beenbrought from the slip engagement state into the direct engagement state.After it is determined that the second clutch CL2 has been transitionedto the direct engagement state, the second clutch operation controlsection 45 a gradually raises a hydraulic pressure to be supplied to thesecond clutch CL2, and raises the supplied hydraulic pressure stepwiseto the complete engagement pressure at time T06, at which apredetermined time has elapsed, to bring the second clutch CL2 into thedirect engagement state. Consequently, mode switching is made from thesecond slip travel mode to the parallel travel mode, and travel in theparallel travel mode is started at and after time T06. In theembodiment, the hydraulic pressure regulation control which has beendescribed above is executed. Thus, even if a certain amount of error iscaused in the actual internal combustion engine torque Te, a torquedifference caused when the second clutch CL2 is transitioned from theslip engagement state to the direct engagement state can be suppressedat the time of mode switching from the second slip travel mode to theparallel travel mode. Thus, it is possible to avoid the possibility thatthe occupants of the vehicle 6 feel a shock as much as possible.

5. Other Embodiments

Lastly, control devices according to other embodiments of the presentinvention will be described. A configuration disclosed in each of thefollowing embodiments may be applied in combination with a configurationdisclosed in any other embodiment unless any contradiction occurs.

(1) In the embodiment described above, in the second slip travel mode,the first clutch CL1 is brought into the direct engagement state and thesecond clutch CL2 is brought into the slip engagement state, andoccurrence of a torque difference at the time of mode switching from thesecond slip travel mode to the parallel travel mode can be suppressedthrough the hydraulic pressure regulation control for the second clutchCL2. However, embodiments of the present invention are not limitedthereto. That is, in one preferred embodiment of the present invention,in the second slip travel mode, for example, the second clutch CL2 isbrought into the direct engagement state and the first clutch CL1 isbrought into the slip engagement state. In this case, in the second sliptravel mode, the rotary electric machine 12 is subjected to the torquecontrol performed in accordance with the target torque Tmf decided bythe target torque decision section 43 a.

FIG. 5 shows a time chart for the starting control and the hydraulicpressure regulation control executed in this case. Also in the example,the hydraulic pressure regulation control has been started at the sametime as the starting control is started. In the example, when therotational speed of the rotary electric machine 12 and the intermediateshaft M rises and the difference in rotational speed between the twoengagement members on both sides of the second clutch CL2 (which is thedifference in rotational speed between the rotary electric machine 12and the intermediate shaft M and the transmission intermediate shaft Sin the example) becomes equal to or less than a third synchronizationdetermination threshold Th4 at time T13 in the course of time, thesecond clutch operation control section 45 a determines that the secondclutch CL2 has been brought from the slip engagement state into thedirect engagement state. After it is determined that the second clutchCL2 has been transitioned to the direct engagement state, the secondclutch operation control section 45 a gradually raises a hydraulicpressure to be supplied to the second clutch CL2, and raises thesupplied hydraulic pressure stepwise to the complete engagement pressureat time T14, at which a predetermined time has elapsed, to bring thesecond clutch CL2 into the direct engagement state. In this case, thesame issue as that in the embodiment described above may be caused atthe time of mode switching from the first slip travel mode to the secondslip travel mode made during the starting control. Even in such a case,however, it is possible to suppress occurrence of a torque differencewhen the second clutch CL2 is transitioned from the slip engagementstate to the direct engagement state and to avoid the possibility thatthe occupants of the vehicle 6 feel a shock as much as possible byexecuting the hydraulic pressure regulation control for the secondclutch CL2 in the example.

In the second slip travel mode, when the rotational speed of thetransmission intermediate shaft S and the rotary electric machine 12rises along with a rise in vehicle speed and the difference inrotational speed between the two engagement members on both sides of thefirst clutch CL1 (which is the difference in rotational speed betweenthe rotary electric machine 12 and the internal combustion engine 11 inthe example) becomes equal to or less than a fourth synchronizationdetermination threshold Th5 at time T15 in the course of time, the firstclutch operation control section 44 determines that the first clutch CL1has been brought from the slip engagement state into the directengagement state. After it is determined that the first clutch CL1 hasbeen transitioned to the direct engagement state, the first clutchoperation control section 44 gradually raises a hydraulic pressure to besupplied to the first clutch CL1, and raises the supplied hydraulicpressure stepwise to the complete engagement pressure at time T16, atwhich a predetermined time has elapsed, to bring the first clutch CL1into the direct engagement state. Thus, mode switching from the secondslip travel mode to the parallel travel mode is made.

(2) In the embodiment described above, the torque error ΔT (correctiontorque Tmb) caused by an error in actual internal combustion enginetorque Te becomes zero when the second clutch CL2 is transitioned to thedirect engagement state through the hydraulic pressure regulationcontrol, and control for the rotary electric machine 12 is immediatelytransitioned from the rotational speed control to the torque control. Insome cases, however, the torque error ΔT may not become completely zerowhen the second clutch CL2 is transitioned to the direct engagementstate (see time T23 of FIG. 6) even if the hydraulic pressure regulationcontrol is executed. In such cases, it is preferable that the rotaryelectric machine control section 43 is configured to execute transitiontorque control in which the rotary electric machine torque Tm isgradually varied from torque (Tmf+Tmb) produced during the rotationalspeed control to the target torque Tmf in the torque control along witha transition from the rotational speed control to the torque control.FIG. 6 shows how the rotary electric machine torque Tm is graduallyvaried at a constant time variation rate to finally coincide with thetarget torque Tmf in the transition torque control (represented as“transition control”) executed from time T23 to time T24. With aconfiguration in which such transition torque control is executed,occurrence of a torque difference can be suppressed by gradually varyingthe rotary electric machine torque Tm to the target torque Tmf even inthe case where the second clutch CL2 is transitioned to the directengagement state when the torque error ΔT is not zero.

(3) In the embodiment described above, the rotational speed control forthe first clutch CL1 is executed with both the first clutch CL1 and thesecond clutch CL2 in the slip engagement state, and the hydraulicpressure regulation control is executed with the internal combustionengine torque Te transferred to the wheels 15. However, embodiments ofthe present invention are not limited thereto. That is, the internalcombustion engine torque Te is transferred as it is to the rotaryelectric machine 12 side even when the internal combustion engine torqueTe is transferred to the wheels 15 with the first clutch CL1 in thedirect engagement state and the second clutch CL in the slip engagementstate, for example. Also with the configuration in which the hydraulicpressure regulation control is executed in such a situation, the sameeffect as that of the embodiment described above can be obtained.

(4) In the embodiment described above, the hydraulic pressure regulationcontrol section 47 starts the hydraulic pressure regulation control atthe same time as the starting control is started, in other words, thehydraulic pressure regulation control section 47 executes the hydraulicpressure regulation control continuously during a period after thesecond clutch CL2 is brought into the slip engagement state and beforethe second clutch CL2 is transitioned to the direct engagement state.However, embodiments of the present invention are not limited thereto.That is, the hydraulic pressure regulation control section 47 mayexecute the hydraulic pressure regulation control at least in a periodafter the second clutch CL2 is brought into the slip engagement stateand before the second clutch CL2 is transitioned to the directengagement state. In one preferred embodiment of the present invention,the hydraulic pressure regulation control section 47 is configured tostart the hydraulic pressure regulation control after a predeterminedtime elapses from the start of the starting control, for example.

(5) In the embodiment described above, the hydraulic pressure regulationcontrol section 47 executes the hydraulic pressure regulation controlwhen the vehicle 6 starts to travel. However, embodiments of the presentinvention are not limited thereto. That is, in one preferred embodimentof the present invention, the slip travel mode is established in thecase where the vehicle speed is reduced to establish a “low vehiclespeed state” during travel in the parallel travel mode, for example, andthe hydraulic pressure regulation control section 47 executes thehydraulic pressure regulation control during travel in the slip travelmode. Also in such a case, the same effect as that of the embodimentdescribed above can be obtained.

(6) In the embodiment described above, the hydraulic pressure regulationcontrol section 47 executes the hydraulic pressure regulation control onthe basis of the correction torque Tmb (torque error ΔT) calculated withthe exclusion of an amount corresponding to the rotation-varying torqueTmi. However, embodiments of the present invention are not limitedthereto. That is, in one preferred embodiment of the present invention,the hydraulic pressure regulation control section 47 is configured toexecute the hydraulic pressure regulation control using the correctiontorque Tmb calculated by the correction torque computing unit 52 as itis without the exclusion of an amount corresponding to therotation-varying torque Tmi.

(7) In the embodiment described above, the hydraulic pressure regulationcontrol is executed in order to suppress a torque difference that may becaused by an error in actual internal combustion engine torque Te.However, embodiments of the present invention are not limited thereto.That is, in the case where the correction torque Tmb is calculated onthe basis of some factor (such as an error in actual transfer torquecapacity Tc2 of the second clutch CL2, for example) during therotational speed control for the rotary electric machine 12, a torquedifference may be caused when the second clutch CL2 is transitioned tothe direct engagement state as in the embodiment described above. Alsoin this case, with the hydraulic pressure regulation control accordingto the present invention, a torque difference can be suppressedirrespective of the factor causing the torque difference.

(8) In the embodiment described above, in order to execute the hydraulicpressure regulation control with high following performance, thehydraulic pressure regulation control section 47 includes both thetarget torque capacity computing unit 53 and the torque capacitycorrection amount computing unit 55, and decides the second clutchtorque capacity command Cc2 on the basis of the target torque capacityTcf and the torque capacity correction amount Tcb calculated by thetarget torque capacity computing unit 53 and the torque capacitycorrection amount computing unit 55, respectively. However, embodimentsof the present invention are not limited thereto. That is, in onepreferred embodiment of the present invention, for example, thehydraulic pressure regulation control section 47 is configured not toinclude the target torque capacity computing unit 53 but to include onlythe torque capacity correction amount computing unit 55, whichcalculates the torque capacity correction amount Tcb which is calculatedby the torque capacity correction amount computing unit 55 as it is asthe second clutch torque capacity command Cc2. Also with thisconfiguration, the same effect as that of the embodiment described abovecan be obtained.

(9) In the embodiment described above, the first clutch CL1 serving asthe “first friction engagement device” and the second clutch CL2 servingas the “second friction engagement device”, which are provided in thedrive device 1 to be controlled by the control device 4, are each ahydraulically driven friction engagement device, the engagement pressureof which is controlled in accordance with a supplied hydraulic pressure.However, embodiments of the present invention are not limited thereto.That is, the first friction engagement device and the second frictionengagement device may each be any friction engagement device, thetransfer torque capacity of which can be regulated in accordance with anincrease and a decrease in engagement pressure. In one preferredembodiment of the present invention, one or both of the first frictionengagement device and the second friction engagement device are each anelectromagnetic friction engagement device, the engagement pressure ofwhich is controlled in accordance with a generated electromagneticforce.

(10) In the embodiment described above, in the drive device 1 to becontrolled by the control device 4, the second clutch CL2 for shifting,which is one of the plurality of friction engagement devices provided inthe speed change mechanism 13, is used as the “second frictionengagement device”. However, embodiments of the present invention arenot limited thereto. That is, in one preferred embodiment of the presentinvention, another clutch, brake, etc. provided in the speed changemechanism 13 is used as the “second friction engagement device”, forexample. In the case where the second friction engagement device is abrake provided in the speed change mechanism 13, a non-rotary membersuch as a drive device case is coupled to an engagement member on oneside of the brake so that the rotational speed of the engagement memberis zero at all times.

(11) In the embodiment described above, in the drive device 1 to becontrolled by the control device 4, the second clutch CL2 for shiftingprovided in the speed change mechanism 13 is used as the “secondfriction engagement device”. However, embodiments of the presentinvention are not limited thereto. That is, a clutch that is provided inthe speed change mechanism 13 but that is not a clutch for shifting maybe used as the “second friction engagement device” as long as the clutchis a friction engagement device provided between the rotary electricmachine 12 and the output shaft O on the power transfer path thatconnects between the input shaft I and the output shaft O. For example,in one preferred embodiment of the present invention, in the case wherea fluid transmission apparatus such as a torque converter is providedbetween the rotary electric machine 12 and the speed change mechanism13, a lock-up clutch of the torque converter is used as the “secondfriction engagement device”. In an alternative preferred embodiment ofthe present invention, a dedicated transfer clutch provided between therotary electric machine 12 and the speed change mechanism 13, or betweenthe speed change mechanism 13 and the output shaft O, for example, isused as the “second friction engagement device”. In such cases, anautomatic continuously variable transmission, a stepped manualtransmission, and a transmission with a fixed speed ratio may be used asthe speed change mechanism 13 in place of a stepped automatictransmission. In addition, the position of the speed change mechanism 13may be set as desired.

(12) In the embodiment described above, the internal combustion enginecontrol unit 30 which mainly controls the internal combustion engine 11and the drive device control unit 40 (control device 4) which mainlycontrols the rotary electric machine 12, the first clutch CL1, and thespeed change mechanism 13 are provided individually. However,embodiments of the present invention are not limited thereto. That is,in one preferred embodiment of the present invention, the single controldevice 4 is configured to control all of the internal combustion engine11, the rotary electric machine 12, the first clutch CL1, the speedchange mechanism 13, etc, for example. In an alternative preferredembodiment of the present invention, the control device 4 is configuredto further individually include a control unit that controls the rotaryelectric machine 12 and a control unit that controls various othercomponents. The allotment of the functional sections described inrelation to the embodiment described above is merely illustrative, and aplurality of functional sections may be combined with each other, or asingle functional section may be further divided into sub-sections.

(13) Also regarding other configurations, the embodiment disclosedherein is illustrative in all respects, and the present invention is notlimited thereto. That is, a configuration not described in the claims ofthe present invention may be altered without departing from the objectof the present invention.

The present invention may be suitably applied to a control device thatcontrols a vehicle drive device in which a rotary electric machine isprovided in a power transfer path that connects between an internalcombustion engine and wheels and in which a first friction engagementdevice is provided between the internal combustion engine and the rotaryelectric machine and a second friction engagement device is providedbetween the rotary electric machine and the wheels.

The invention claimed is:
 1. A control device that controls a vehicledrive device in which a rotary electric machine is provided in a powertransfer path that connects between an internal combustion engine andwheels and in which a first friction engagement device is providedbetween the internal combustion engine and the rotary electric machineand a second friction engagement device is provided between the rotaryelectric machine and the wheels, wherein: the control device executesrotational state control in which a rotational state of the rotaryelectric machine is controlled such that a target rotational state isestablished with torque of the internal combustion engine transferred tothe wheels while a hydraulic pressure supplied to the first frictionengagement device is controlled such that a rotational state of theinternal combustion engine coincides with a target rotational state withboth the first friction engagement device and the second frictionengagement device in a slip engagement state, or with torque of theinternal combustion engine transferred to the wheels with the firstfriction engagement device in a direct engagement state and with thesecond friction engagement device in a slip engagement state; and thecontrol device executes hydraulic pressure regulation control in which ahydraulic pressure supplied to the second friction engagement device inthe slip engagement state is controlled on the basis of torque of therotary electric machine produced during the rotational state controlwhile the second friction engagement device is transitioned from theslip engagement state to a direct engagement state, wherein: the controldevice further executes target torque decision control in which targettorque for the rotary electric machine is decided on the basis of adifference between a required drive force for driving the wheels andtorque transferred from the internal combustion engine to the rotaryelectric machine; the control device executes as the rotational statecontrol rotational speed feedback control in which a rotational speed ofthe rotary electric machine is controlled so as to coincide with atarget rotational speed by adding correction torque to the targettorque; and the control device executes the hydraulic pressureregulation control on the basis of the required drive force and thecorrection torque for the rotational speed feedback control.
 2. Thecontrol device according to claim 1, wherein the control device executesthe hydraulic pressure regulation control on the basis of the correctiontorque calculated with exclusion of an amount corresponding torotation-varying torque for the rotary electric machine for varying therotational speed of the rotary electric machine toward the targetrotational speed in the rotational speed feedback control.
 3. Thecontrol device according to claim 1, wherein in the hydraulic pressureregulation control, a target transfer torque capacity for the secondfriction engagement device is decided on the basis of a value computedby integrating the correction torque over time, and the hydraulicpressure supplied to the second friction engagement device is decided onthe basis of the target transfer torque capacity.
 4. The control deviceaccording to claim 1, wherein the control device can further executetorque control in which output torque of the rotary electric machine iscontrolled so as to coincide with the target torque; and in the casewhere it is determined during execution of the hydraulic pressureregulation control that the second friction engagement device has beenbrought into the direct engagement state, control for the rotaryelectric machine is transitioned from the rotational speed feedbackcontrol to the torque control.
 5. The control device according to claim2, wherein the control device can further execute torque control inwhich output torque of the rotary electric machine is controlled so asto coincide with the target torque; and in the case where it isdetermined during execution of the hydraulic pressure regulation controlthat the second friction engagement device has been brought into thedirect engagement state, control for the rotary electric machine istransitioned from the rotational speed feedback control to the torquecontrol.
 6. The control device according to claim 3, wherein the controldevice can further execute torque control in which output torque of therotary electric machine is controlled so as to coincide with the targettorque; and in the case where it is determined during execution of thehydraulic pressure regulation control that the second frictionengagement device has been brought into the direct engagement state,control for the rotary electric machine is transitioned from therotational speed feedback control to the torque control.
 7. The controldevice according to claim 4, wherein in the case where the correctiontorque has not become zero when it is determined that the secondfriction engagement device has been brought into the direct engagementstate, the control device executes transition torque control in whichthe output torque of the rotary electric machine is gradually variedfrom torque produced during the rotational speed feedback control to thetarget torque along with the transition from the rotational speedfeedback control to the torque control.
 8. The control device accordingto claim 5, wherein in the case where the correction torque has notbecome zero when it is determined that the second friction engagementdevice has been brought into the direct engagement state, the controldevice executes transition torque control in which the output torque ofthe rotary electric machine is gradually varied from torque producedduring the rotational speed feedback control to the target torque alongwith the transition from the rotational speed feedback control to thetorque control.
 9. The control device according to claim 6, wherein inthe case where the correction torque has not become zero when it isdetermined that the second friction engagement device has been broughtinto the direct engagement state, the control device executes transitiontorque control in which the output torque of the rotary electric machineis gradually varied from torque produced during the rotational speedfeedback control to the target torque along with the transition from therotational speed feedback control to the torque control.
 10. The controldevice according to claim 1, wherein the hydraulic pressure regulationcontrol is executed in a predetermined period at and before a time atwhich the second friction engagement device is transitioned from theslip engagement state to the direct engagement state, the predeterminedperiod including the time of the transition.
 11. The control deviceaccording to claim 1, wherein the control device executes the hydraulicpressure regulation control continuously in a period after the secondfriction engagement device is brought into the slip engagement state andbefore the second friction engagement device is transitioned to thedirect engagement state.
 12. The control device according to claim 1,wherein in the hydraulic pressure regulation control, a target transfertorque capacity for the second friction engagement device is decided onthe basis of torque of the rotary electric machine necessary to causethe rotational state of the rotary electric machine during therotational state control to coincide with the target rotational state,and the hydraulic pressure supplied to the second friction engagementdevice is decided on the basis of the target transfer torque capacity.